1. Field of the Invention
This invention relates to an image generation device and an information storage medium for generating an image that enables a player to use a shooting device to shoot at a target object within an object space.
2. Description of Related Art
Image generation devices have been developed and implemented in the art, to enable a player to use a shooting device such as a handgun-shaped controller to shoot at a target object. When a player 520 pulls a trigger of a handgun-shaped controller 522 of such an image generation device, as shown in FIG. 1A, a two-dimensional position on a display screen 512 that is indicated by the handgun-shaped controller 522 is optically detected. If the thus-detected two-dimensional position matches the position of a two-dimensional target object that is displayed on the screen, this is determined to be a hit; if it does not match, this is determined to be a miss. This image generation device makes it possible for a player to enjoy the virtual experience of target-shooting or gun-fighting without using a real firearm, so it is highly popular as a game.
When a plurality of players play on an image generation device of this type (with a multi-player game), first and second players 520-1 and 520-2 both use the same display screen 512 in common, as shown in FIG. 1B. In other words, the viewpoints of the first and second players 520-1 and 520-2 within the object space are the same, and the first and second players 520-1 and 520-2 shoot by aiming at a target object seen from the same viewpoint.
A technical problem with this sort of image generation device is how to increase the sensation of virtual realism that is felt by the players. One method that could be considered for improving this virtual realism is to play (or replay, animate) the motion of a target object on the basis of previously prepared motion data when a shot fired by a player has hit the target object.
However, the motion of the target object that is played in this manner lacks realism and is monotonous, so that it is insufficient for solving the technical problem of improving the feeling of virtual reality.
This invention was devised in the light of the above described technical problems and has as an objective thereof the provision of an image generation device and information storage medium that make it possible to increase the realism and variety of motions of target objects.
In order to address the above described technical problems, there is provided an image generation device for generating an image that enables at least one player to use a shooting device to shoot at at least one target object within an object space, according to a first aspect of the present invention. The image generation device comprises: means for processing for setting a plurality of objects, including a target object, within the object space; means for performing a hit check between a shot from the player and a target object; means for storing motion data for a target object; means for playing the motion of a target object on the basis of the motion data, when a shot has hit the target object, and also varying the motion of the target object in accordance with the direction of the trajectory of the shot that has hit the target object; and means for generating an image as seen from a given viewpoint within the object space.
According to a second aspect of the present invention, there is provided an information storage medium used in an image generation device for generating an image that enables at least one player to use a shooting device to shoot at at least one target object within an object space. The information storage medium comprises: information for processing for setting a plurality of objects, including a target object, within the object space; information for performing a hit check between a shot from the player and a target object; information for storing motion data for a target object; information for playing the motion of a target object on the basis of the motion data when a shot has hit the target object, and also varying the motion of the target object in accordance with the direction of the trajectory of the shot that has hit the target object; and information for generating an image as seen from a given view-point within the object space.
With the image generation device and the information storage medium of this invention, the motion of the target object varies (or changes) in accordance with the direction of the trajectory of a shot from a player. When the target object is shot from in front, for example, a realistic motion is played to indicate that the target object has been shot from in front. Similarly, if the target object is shot from the left, from the rear, or from the right, a realistic motion is played (or replayed, animated) to indicate that the target object has been shot from the left, from the rear, or from the right, respectively. This makes it possible to greatly increase the realism and degree of variety of target object motions, improving the feeling of a virtual reality that the player experiences.
In the image generation device and the information storage medium of this invention, when a plurality of players are playing a game, the motion of a target object may be varied in accordance with which player""s shot has hit the target object. Such a configuration makes it possible to further increase the degree of variety of motions of the target objects. It also means that there is no need to determine the direction of the shot trajectory directly, enabling motion play in accordance with the trajectory direction.
In the image generation device and the information storage medium of this invention, the motion of a target object may be varied in accordance with the hit portion of the target object that has been hit by a shot. This makes it possible to increase the degree of variety of motions, by playing motions that differ for different hit portions (or hit resions, hit locations), even when the direction of the shot trajectory is the same.
Note that in the image generation device and the information storage medium of this invention, the motion of a target object may be varied on the basis of an angle between the direction of the trajectory of a shot that has hit the target object and the direction in which the target object is facing.
In such a case, an angular range that contains the angle may be determined from a given plurality of angular ranges, and the motion of the target object may be played on the basis of motion data that has been set to the angular range that contains that angle. This makes it possible to reduce the storage capacity necessary for the motion data storage means, reducing the overall size of the hardware.
The orientation of a target object during motion play may be corrected on the basis of this angle. This makes it possible to play an accurate motion in a natural manner in accordance with this angle.
In the image generation device and the information storage medium of this invention, an image as seen from a first viewpoint in the object space may be generated and the thus generated image may be output to a first display screen for a first player; and an image as seen from a second viewpoint in the object space may be generated and the thus generated image may be output to a second display screen for a second player. With this configuration, a first player can enjoy shooting at target objects while viewing an image from a first viewpoint within the object space, and a second player can enjoy shooting at target objects while viewing an image from a second viewpoint within the object space. This makes it possible to greatly increase the feeling of a virtual reality and the dramatic effect of the game that the players experience, in comparison with the prior-art example in which the viewpoints of the first and second players are the same. It prevents uniformity of the displayed images and enables an increase in the degree of variety of the images. In addition, the virtual realities experienced by the first and second player can be made to differ.
In the image generation device and the information storage medium of this invention, the direction of the trajectory of a shot from the first player may be specified on the basis of the first viewpoint and a two-dimensional position on the first display screen indicated by a shooting device of the first player, and a hit check may be performed and the motion of the target object may be varied on the basis of the thus specified trajectory direction. The direction of the trajectory of a shot from the second player may also be specified on the basis of the second viewpoint and a two-dimensional position on the second display screen indicated by a shooting device of the second player, and a hit check may be performed and the motion of the target object may be varied on the basis of the thus specified trajectory direction. This makes it possible to perform a hit check from consideration of the trajectory direction, further increasing the realism of the game.
In the image generation device and the information storage medium of this invention, the motion of the target object may be varied in accordance with whether or not a given condition has been met since the target object was generated. This makes it possible to vary the motion of a target object in accordance with whether or not a given condition has been met, in addition to the direction of the shot trajectory. The degree of variety of target object motions can be increased thereby, and it is also possible to implement motion play that is not inconsistent.
Note that this condition could be any of various conditions, such as a condition relating to whether or not a given time has elapsed since the target object was generated, a condition relating to whether or not the motion play of a target object has been repeated a given number of times since the target object was generated, or a condition relating to whether or not an object relating to the motion play of a target object has disappeared since the target object was generated.